The Crusades in the middle ages had different reflections in political and Economic circumstances of the Western Europe and the Eastern Islamic lands. One of the most important of these reflections was the trade that the West benefited much from it. This paper seeks to use the library resources and a descriptive-analytic method to evaluate the factors affecting the West's trade exploitation and development in the East. European authorities, after general mobilization of Christians and success in the crusades, created colonies in the east of Mediterranean Sea, dominated the direct exchanges of merchandise from the East to the West and taxed the merchants and shipping vessels. Colonialism, along with feudalism, monopolization of commodity exchanges, taxation and the establishment of branches led to the development of the commercial exploitation of European traders in the East, boosted the Mediterranean business and promoted the economic wealth and civilization of Western Europe.